How many porta potties do I need?
Plan on 1 standard porta potty for every 50 guests at an event up to 4 hours. Add 1 more per 100 guests if the event runs longer, and 1 more per 100 guests if alcohol is served. Construction sites follow OSHA's count instead. The calculator and tables below do the math for you.
How many porta potties do I need for my event?
You need 1 standard porta potty per 50 guests for an event up to 4 hours, rounded up. Add 1 unit per 100 guests when the event runs over 4 hours. Add 1 more unit per 100 guests when alcohol is served. Add a handwashing station for every 2 units when food is served.
Enter your headcount below. The calculator shows the count and each step of the math, so you can check it yourself.
You need
standard units,
Method: 1 unit per 50 guests, plus 1 per 100 guests for events over 4 hours, plus 1 per 100 guests when alcohol is served. Planning numbers, not a code requirement.
The calculator gives standard units. One of them should be wheelchair-accessible at any public event. See the rental cost guide to price the count it gives you.
Why 1 porta potty per 50 guests?
One porta potty per 50 guests works because the limit at a party is the line, not the tank. A standard porta potty holds about 200 uses between cleanings, more than 50 guests usually use in 4 hours. The extra units for long events and drinking keep the line short when everyone goes at once.
Guests do not spread their visits evenly. Lines form right after dinner, after the toasts and at the end of the night. That is why the method adds units for time and for alcohol instead of just counting heads.
These are planning numbers from our own setups, not a code requirement. Building codes and OSHA rules apply to buildings and workplaces, and we cover those further down.
The assumptions behind the method
- Every unit is a standard porta potty. A deluxe flushing unit counts as one unit, but its flush tank runs low after roughly 50 to 75 flushes.
- Guests are adults and teens. Kids' parties need about the same count, because kids need help and take longer.
- Units sit in one or two groups close to the action, not spread around a large property.
- No cleaning happens during the event. Multi-day events need a service visit, covered below.
How many porta potties for 25 to 500 guests?
The quick-reference table gives the standard porta potty count for 25 to 500 guests. Find your headcount, then read across for event length and alcohol. For example, 100 guests need 2 units for a short party, 3 for a party over 4 hours, and 4 if the long party has a bar.
| Guests | Up to 4 hours | Over 4 hours | Up to 4 hours, with alcohol | Over 4 hours, with alcohol | Handwashing stations if food (last column) |
|---|---|---|---|---|---|
| 25 | 1 | 2 | 2 | 3 | 2 |
| 50 | 1 | 2 | 2 | 3 | 2 |
| 75 | 2 | 3 | 3 | 4 | 2 |
| 100 | 2 | 3 | 3 | 4 | 2 |
| 125 | 3 | 5 | 5 | 7 | 4 |
| 150 | 3 | 5 | 5 | 7 | 4 |
| 200 | 4 | 6 | 6 | 8 | 4 |
| 250 | 5 | 8 | 8 | 11 | 6 |
| 300 | 6 | 9 | 9 | 12 | 6 |
| 400 | 8 | 12 | 12 | 16 | 8 |
| 500 | 10 | 15 | 15 | 20 | 10 |
Counts are standard units, rounded up. Handwashing stations are 1 per 2 units, rounded up, for the over-4-hours-with-alcohol column. Swap in deluxe units with sinks and you can drop the stations.
Have your number?
Call Shawn with the count and the date. Shawn gives you the price and a delivery day before you hang up.
What do real porta potty counts look like?
Real porta potty counts follow the same three steps every time: guests divided by 50, then extra units for time and alcohol, then handwashing for food. Here are three Erie-style events worked out line by line, from a backyard graduation party to a wedding with a bar to an all-day festival.
Graduation open house, 80 guests, 5 hours, food, no alcohol
80 ÷ 50 = 1.6, rounded up to 2 units. Over 4 hours adds 1 (80 ÷ 100, rounded up). That is 3 standard units plus 2 handwashing stations. Another good fit is 2 standard units and 1 deluxe unit with a sink, plus 1 station. More ideas are in the graduation party guide.
Wedding, 150 guests, 6 hours, with a bar
150 ÷ 50 = 3 units. Over 4 hours adds 2 (150 ÷ 100 = 1.5, rounded up). The bar adds 2 more. That is 7 units, with 1 wheelchair-accessible, plus 4 handwashing stations (7 ÷ 2, rounded up). Or rent one 2-room restroom trailer plus 3 standard units. See wedding restrooms for both layouts.
Community festival, 300 guests, 8 hours, beer tent
300 ÷ 50 = 6 units. Over 4 hours adds 3. Alcohol adds 3. That is 12 units. Split into two groups of 6, each group needs its own accessible unit, so 2 of the 12 are accessible. Add 6 handwashing stations near the food. The festival rentals page covers attendant service.
How do I count porta potties for a construction crew?
OSHA requires 1 toilet for 20 or fewer workers on a construction site. From 20 workers up, the rule is 1 toilet seat and 1 urinal per 40 workers. From 200 workers up, the rule is 1 seat and 1 urinal per 50 workers. The rule is 29 CFR 1926.51(c), Table D-1.
| Workers on site | OSHA minimum (Table D-1) | Our recommendation, weekly service |
|---|---|---|
| 1 to 10 | 1 toilet | 1 standard unit |
| 11 to 20 | 1 toilet | 2 standard units |
| 30 | 1 seat and 1 urinal | 3 standard units |
| 40 | 1 seat and 1 urinal | 4 standard units |
| 60 | 2 seats and 2 urinals | 6 standard units |
| 100 | 3 seats and 3 urinals | 10 standard units |
| 200 | 4 seats and 4 urinals | Sized with you, often twice-weekly service |
Source: OSHA 29 CFR 1926.51. Our recommendation is not the law. It is 1 unit per 10 workers on a 40-hour week, so the units stay usable between weekly cleanings.
The legal minimum keeps you out of trouble on paper. Twenty workers sharing one unit for a full week will fill it well before the next service, and a full unit is a unit nobody uses. Add a unit or move to twice-weekly service.
Crews that move from site to site with a truck nearby may fall under the mobile-crew exception. Our OSHA guide for Pennsylvania jobsites walks through it, and construction site toilets covers jobsite delivery and billing.
How many porta potties does a farm need for field workers?
A farm needs 1 toilet and 1 handwashing facility for every 20 field workers, under OSHA 29 CFR 1928.110. The rule covers farms with 11 or more hand laborers in the field on a given day. The toilet and the sink must sit within a quarter-mile walk of where people work.
The count rounds up: 21 workers means 2 toilets and 2 handwashing facilities. The rule does not apply to field work of 3 hours or less, including travel to and from the field.
If the terrain makes a quarter-mile walk impossible, the units go at the closest point a vehicle can reach. Read the full text at OSHA 1928.110. For a harvest season, a seasonal rental with weekly service keeps the units in the field.
How many wheelchair-accessible porta potties do I need?
Plan at least 1 wheelchair-accessible porta potty in every group of units. The 2010 ADA Standards, section 213.2, say at least 5% of portable toilets in each cluster must be accessible where toilets are provided. A cluster of 1 to 20 units needs 1. A cluster of 21 to 40 units needs 2.
The key word is cluster. Two groups of 6 units on opposite ends of a fairground need 1 accessible unit each, not 1 for the whole event. Read section 213.2 at the U.S. Access Board.
Our wheelchair-accessible unit has a ground-level entry, grab bars and a 60-inch turning circle. It needs a flat, firm spot about 8 by 8 feet, close to a hard path.
How many handwashing stations go with my porta potties?
Plan 1 handwashing station for every 2 porta potties when food is served, with a minimum of 1. Each station has 2 sinks, so two people wash at once, and one fill handles about 300 to 400 hand washes. Deluxe flushing units have a sink inside, so they need no extra station.
Put the stations between the toilets and the food line, not behind the units. People wash when the sink is in their path.
On a jobsite, OSHA 1926.51(f) requires washing facilities where workers handle paint, coatings or other harmful substances. We put a handwashing station on most sites anyway. Crews eat lunch on site.
How many porta potties does a restroom trailer replace?
A 2-room restroom trailer replaces about 3 standard porta potties for an evening event. One trailer serves about 100 guests over 5 hours. For bigger crowds, pair the trailer with standard units: a 150-guest wedding with a bar works with one trailer plus 3 standard units, one of them wheelchair-accessible.
A trailer has steps, so it does not replace the accessible unit. It also needs a 110V, 20-amp outlet within 50 feet and a garden hose. Details are on the restroom trailer page.
When should I add a second cleaning instead of more units?
Add a second cleaning when the same porta potties get heavy use for more than one day. A standard unit holds about 200 uses between cleanings. Two-day festivals, busy campgrounds and jobsites with more than 10 workers per unit fill up before the next visit. An extra cleaning costs $45 per unit.
For a one-day party, more units beat a mid-event cleaning. The truck would arrive in the middle of your event, and the line problem is about people at once, not the tank.
For multi-day events, a pump-out each night keeps the count the same and the units fresh. Monthly jobsite units can move to twice-weekly service for an added cost.
Porta potty count questions
These porta potty count questions cover small parties, separate units for men and women, deluxe units, overnight events and what happens if you guess too low. Each answer gives the number first. When in doubt, call Shawn with your headcount and he will size the order with you.
Is one porta potty enough for a party of 40?
One standard porta potty is enough for 40 guests at a party up to 4 hours. Over 4 hours or with alcohol, the method calls for 2. Many hosts add a second unit anyway so there is a spare.
Should I get one for men and one for women?
Two units split men's and women's is a good idea once you have 2 units anyway. The men's unit can be a standard with a urinal. The women's unit can be a deluxe flushing unit with a sink.
Do deluxe flushing units count the same as standard units?
A deluxe flushing unit counts as one unit, but its flush tank lasts about 50 to 75 flushes. For more than about 50 guests, pair deluxe units with standard units or book a refill.
What if I order too few?
Lines get long and the units get messy fast. If you are between two numbers, round up. In the Erie core zone we can often add a unit the same day if you call by 11 a.m.
Do kids count as guests?
Count kids as full guests. They visit often, need help, and take longer. A kids' birthday party uses the same table as an adult party without alcohol.
How many units for an overnight camping event?
Start with the over-4-hours column, then book a cleaning each morning. Overnight events mean every guest uses the units several times. See campground rentals for longer stays.
Get your itemized quote
Fastest way: call Shawn. You get the price, the delivery day and the total on one call.
(814) 245-2757Mon–Sat, 7 a.m.–7 p.m. Calls are answered in Erie, not a call center.
On a jobsite? Text the address and a photo of the spot to (814) 245-2757.
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